Modified centrifugal pump



March 5, 1963 e. D. WALKER 3,079,866

MODIFIED CENTRIFUGAL PUMP Filed July 16, 1959 llnited iitates harem 73,979,865 MGDHF IE1) SENTREFUGAL PUB/ll George D. Walker, Port Arthur,Tex, assignor to Texaco, inc, New York, N.Y., a corporation of BelawareFiled July 16, I359, Ser. No. 827,472 4 Claims. (til. 193-103) Thisinvention relates generally to centrifugal pumps and in one specificaspect, relates to a single stage, centrifugal pump for operation withliquids containing an appreciable amount of suspended solids.

Single stage, centrifugal pumps are characterized by shrouded impellersand a reduction in the width of the volutes or spiral vanes from thejuncture with the hub of the impeller to the periphery. This reductionin width or choice effect is to help impart velocity to the liquid as itis displaced radially along the impeller. It also provides anopportunity for solids, such as coke and the like, in suspension in theliquid being pumped to become lodged in' the passages defined by thevanes and the shrouds of the impeller and to cause plugging or unbalanceof the rotating impeller. In either case, it is necessary to shut downthe pump and to remove the accumulated solids.

Accordingly, it is an object of the present invention to provide animproved centrifugal pump for use with liquids containing a considerableamount of solids.

Another object of the invention is to provide a structure by whichsolids contained in the liquid being pumped may be prevented fromaccumulating in the rotating element.

Still another object of the invention is to provide a modification ofthe impeller of a centrifugal pump which can be used to reduce the sizeof solids carried by a pumped liquid to such small particles that theymay be carried down through the pump without difficulty.

These and other objects, features and advantages of the invention willbecome apparent from the following description when taken in conjunctionwith the FIGURE which is a diagrammatic cross-section of the modifiedcentrifugal pump.

The objects of the invention are attained by modifying the impellerstructure of a pump for liquids having solid particles suspended thereinso that the particles will be ground up and agitated by the impelleracting against a wear plate thereby preventing the plugging action whichnorm-ally occurs with a fully shrouded impeller structure.

Referring to the figure, the pump is indicated generally at 10,consisting of the inlet casing section at 11, and the bearing section orstuffing box extension 12, each formed with recesses to define a chamberfor the impeller 13. Through the stufing box extension 12, there ismounted the drive shaft 14, which is supported by the shaft sleeve at15, with the packing stutfing box at 16 and the stuffing box bushing orpacking sleeve at 17, and the gasket for the shaft sleeve at 18.

The impeller 13 is fastened to the drive shaft 14 by means of thelocking collar at 19, which is fastened in locking position, eg by meansof the cotter pin, as disclosed herein, at 20. The impeller includes ashroud at 21 on the inlet side, annular in cross-section and having anupright cylindrical portion at 22 concentric with the axis of theimpeller 13. The shroud 21 serves to reinforce and define passagesbetween a plurality of spiral vanes or volutes 23 which are mountedbetween the shroud and the hub 24 and define the fiow passages ofdiminishing cross-section in a radial direction, the edge portions ofthe volutes adjacent the bearing section of the pump being free edgeportions as shown at 23a.

At the outer edge of the hub and at the beginning of the free edgeportions of the volu-tes, the impeller has wear ring at 25 of annularshape. On the stufing box extension and in immediate position and incontact with the free edge portions 23a of the volutes 23, and the outercylindrical surface 25a of the wear ring '25, there is an annular wearplate 26, with a flat end surface 26a and which is held in position byappropriate fastening means, shown herein as cap screws 27 together witha plurality of welds at 28. As the liquid containing the suspended solidparticles passes through the passage way defined by the volutes betweenthe shroud 21 and the hub 24, there is a wearing action between the freeedge portions 23a of the volutes in contact with the flat end surface26a of the wear plate which will grind the particles to such a size thatthey will be able to proceed through the pump withotu a packing of theparticles, because of the wiping action across the fiat end surface ofthe wear plate.

The inlet casing section 11 includes the suction eye or inlet portion at2%, and at the edge of the pump chamber, there is positioned the casingWear ring at 3%, fastened in position by the Welds at 31 and whichextends into the chamber and is of such configuration that it is incontact at 39a with the upstream or inlet edges 23' of the volutes 23and at 36b with the inner surface 22a of the upstanding cylindricalportion 22. This forms a seal between the low pressure incoming fluid atthe inlet end of 29 and the pressurized fluid in the chamber indicatedat 32..

Thus there has been shown and described, a modification of a singlestage, centrifugal pump, wherein the shroud is maintained on theupstream side of the' impeller which has volutes on the downstream sidein contact with a wear plate. While the modification of the pump is suchas to allow for construction thereof, it is possible also to modify aconventional double shrouded impeller of a centrifugal pump by removalof the downstream shroud which leaves the hub only to support the vaneson the downstream side of the impeller.

Obviously, other modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore, only such limitations should beimposed as are indicated in the appended claims.

I claim:

1. in combination in a centrifugal pump, a bearing section and an inletcasing section together denfining a pump chamber, an impeller housed insaid chamber and comprising a hub, spiral vanes of diminishing radialcross section supported on that portion of said hub facing said inletcasing section, and a shroud fastened to the edges of said vanes facingsaid inlet casing section starting at the discharge edges thereof andextending inwardly radially partly a ong said vanes facing said inletcasing section thereby defining a single shroud impeller whereby saidvanes on the side facing said bearing section have free edge portions,and a replaceable wear plate supported by said bearing section insliding contact with said free edge portions of said vanes on the sideof said impeller facing said bearing section, said wear plate having acylindrical annular form, said impeller including an annular wear ringsupported by the hub thereof adjacent said free edge portions of saidvanes and of such dimension as to contact the annular wear plate on theinner cylindrical surface thereof.

2. In a centrifugal pump as defined in claim 1, said shroud afterextending inwardly radially partly along said vanes extending upstreamcoaxially with said hub free of said edges of said vanes and defining acylindrical portion extending towards the inlet of said casing section,said casing section at the inlet to said chamber having a casing wearring in sliding contact with said cylindrical portion on the innersurface thereof thereby separating high and low pressure fluids in saidpump chamber.

3. In combination, in a single stage centrifugal pump, an inlet casingsection and a bearing section formed to define a pump chamber whentogether in assembled position, and an impeller mounted within said pumpchamber, said bearing section including means for supporting saidimpeller within said chamber, said impeller including a hub and anannular shroud and spiral vanes having axially opposed edges anddiminishing in cross section a in outward radial direction in joiningrelationship with said hub and said shroud and defining spiral passagestherebetween, saidshroud being supported by the edges of said vanesadjacent the inlet casing section starting at the peripheral edgesthereof and extending partly therealong radially inward and thenupstream coaxially with said hub and" free of said vanes, the edgeportions of said vanes adjacent the bearing section defining said pumpchamber being free edge portions, said bearing section including acylindrical annular wear plate, said wear plate having a flat endsurface in surface to surface contact with said impeller along said freeedge portions of said spiral vanes for wiping action thereagainst duringimpeller rotation, said annular shroud on the upstream coaxiallyextending portion of said impeller being a cylindrical portion inconcentric relationship with the axis of its rotation, said inlet casingsection having a wear member in sliding contact with the inner surfaceof said cylindrical portion of said annular shroud, said impellerincluding a wear ring mounted on said hub and in contact with the innercylindrical surface-of said annular wear plate 4; In combination, in asingle stage centrifugal pump, an inlet casing section and a bearingsection having cornpleinentaryi recesses for defining a pump chamberwhen in: assembled relationship with each other, an impeller for housingin said chamber formed thereby, a drive shaft supported by said bearingsection and mounting said impeller, said impeller including a hub, anannular shroud and spiral vanes of diminishing cross section in outwardradialdimension in supporting relationship with each other and definingspiral passages ofdecreasing crosssection relationship in downstreamflow, said annular shroud being spaced closer toward said inlet casingsection than said spiral vanes starting from the outer radial dischargeedges thereof extending inwardly radially partly along the upstreamedges thereof and having an inner cylindrical portion in concentricrelationship with the axis of rotation of said impeller free of the,upstream edges of a said vanes, said inlet casing section having a wearmeme all) ber in contact with said cylindrical portion and forming aseal between the low pressure inlet fluid and the'high pressure fluiddischarged by said impeller, said vanes having free edge portions indownstream relationship to said annular shroud, and a cylindricalannular wear plate in said bearing section in surface to surfacesliding. cone tact with said free edge portions of said vanes wherebywiping action of said free edge portions of said vanes pref ventsclogging by suspended materials in said passages, said impellerincluding a wear ring. mounted on said hub and in contactwith the innercylindrical surface of said annular wear plate.

References Cited in the file of this patent UNITED STATES PATENTSv538,050 Swabel Apr. 23, 1895 721,207 Lockwood Feb. 24, 1903' 772,532 RayOct. 18,1904 790,795 Lea et a1. May 23, 1905 914,283 Jackson Mar. 2 19091,099,921 Gibson June 16, 1914' 1,743,916 Hargis' Ian'.'14',. 19302,852,009" Tur1ay' e Sept; 16, 1958* FOREIGN PATENTS 1,616 Great Britainof 1899 15,895 Great Britain c of 1907 27,740 Great Britain .a of 191235,354 Norway July 17, 1922' 267,300 Great Britain e Mar. 17,4927442,555 Italy Nov. 25, 1948 495,897 Italy Feb. 28, -1953- 730,459 GreatBritain May 25, 1955'

1. IN COMBINATION IN A CENTRIFUGAL PUMP, A BEARING SECTION AND AN INLETCASING SECTION TOGETHER DEFINING A PUMP CHAMBER, AN IMPELLER HOUSED INSAID CHAMBER AND COMPRISING A HUB, SPIRAL VANES OF DIMINISHING RADIALCROSS SECTION SUPPORTED ON THAT PORTION OF SAID HUB FACING SAID INLETCASING SECTION, AND A SHROUD FASTENED TO THE EDGES OF SAID VANES FACINGSAID INLET CASING SECTION STARTING AT THE DISCHARGE EDGES THEREOF ANDEXTENDING INWARDLY RADIALLY PARTLY ALONG SAID VANES FACING SAID INLETCASING SECTION THEREBY DEFINING A SINGLE SHROUD IMPELLER WHEREBY SAIDVANES ON THE SIDE FACING SAID BEARING SECTION HAVE FREE EDGE PORTIONS,AND A REPLACEABLE WEAR PLATE SUPPORTED BY SAID BEARING SECTION INSLIDING CONTACT WITH SAID FREE EDGE PORTIONS OF SAID VANES ON THE SIDEOF SAID IMPELLER FACING SAID BEARING SECTION, SAID WEAR PLATE HAVING ACYLINDRICAL ANNULAR FORM, SAID IMPELLER INCLUDING AN ANNULAR WEAR RINGSUPPORTED BY THE HUB THEREOF ADJACENT SAID FREE EDGE PORTIONS OF SAIDVANES AND OF SUCH DIMENSION AS TO CONTACT THE ANNULAR WEAR PLATE ON THEINNER CYLINDRICAL SURFACE THEREOF.